[karulont]

Perceptual hashes are quite reversible. It is not a cryptographic hash that is hard to reverse.

[yyyk]

I think the state of the art has progressed past that? A non-trivial reversal of a perceptual hash would mean that every cloud provider maintaining a CSAM scan list violates CSAM laws - if they could reverse the hash to get too close to the original image, the hash is just a lossy storage format.

[ec109685]

Not the way apple implemented it. The hash was encrypted and could only be decrypted if 5 hashes matched a known csam hashes.